Morin enhances hepatic Nrf2 expression in a liver fibrosis rat model

Abstract

Aim: To investigate whether morin can reduce hepatic fibrosis by activating the NF-E2-related factor 2 (Nrf2) signaling pathway.

Methods: Twenty male Sprague-Dawley rats were randomly divided into four groups: control group, morin group, carbon tetrachloride (CCl₄) group, and morin + CCl₄ group. Rats in both the CCl₄ and morin + CCl₄ groups were injected intraperitoneally with CCl₄ at a dose of 2 mL/kg twice a week. Rats in both the morin and morin + CCl₄ groups were treated orally with morin at a dose of 50 mg/kg twice a week. Control rats were treated with vehicle only twice a week. At the end-point of the 8 wk of the experimental period, serum AST, ALT, and ALP were measured, and the liver specimens were obtained for pathological assessment. Real-time PCR and Western blot methods were used to analyze the expression of α-smooth muscle actin (α-SMA), collagen I, collagen III, Nrf2, heme oxygenase (HO-1), and quinone oxidoreductase 1 (NQO1) using frozen liver specimens.

Results: Morin-treated rats in the morin + CCl₄ group had less hyperplasia of fiber tissue, minimal inflammatory cells, and less body weight loss with favorable liver enzyme measurements compared to rats treated with CCl₄ only. Additionally, morin-treated rats had significantly lower mRNA and protein expression of α-SMA, collagen I, and collagen III, but significantly higher mRNA and protein expression of Nrf2, HO-1, and NQO1 compared to rats treated with CCl₄ only (P < 0.05).

Conclusion: Morin could play a protective role by inducing the expression of Nrf2 and its downstream antioxidant factors (HO-1 and NQO1) and reducing the expression of α-SMA, collagen I, and collagen III in CCl₄-induced liver fibrosis rats.

Keywords: Liver fibrosis; Morin; Nrf2; Rat.

Figure 1

Chemical structure of morin. (https://pubchem.ncbi.nlm.nih.gov/compound/morin).

Figure 2

Changes in body weight among different groups. Body weight increased observably in the control and morin groups. The CCl₄ group had slow weight growth, but morin treatment was associated with increased body weight.

Figure 3

Histological changes of liver samples. A: Control group: treated with vehicle only; B: Morin group: treated with morin at a dose of 50 mg/kg twice a week; C: CCl₄ group: injected with CCl₄ at a dose of 2 mL/kg twice a week; D: Morin + CCl₄ group: treated with the same volume of morin and CCl₄ as the morin and CCl₄ groups. Liver tissues were stained with H&E (× 100).

Figure 4

The mRNA expression of α-SMA, collagen I, and collagen III. ^aP < 0.05 vs control group, ^cP < 0.05 vs morin group, ^eP < 0.05 vs CCl₄ group. In the control and morin groups, there was only minimal expression. The CCl₄ and morin + CCl₄ groups showed significantly increased expression (P < 0.05), while the expression levels in the morin + CCl₄ group were lower than those of the CCl₄ group (P < 0.05).

Figure 5

The mRNA expression of HO-1, NQO1, and Nrf2. ^aP < 0.05 vs control group, ^cP < 0.05 vs morin group, ^eP < 0.05 vs CCl₄ group. The expression was increased obviously in the CCl₄ and morin + CCl₄ groups compared to the control and morin groups (P < 0.05). The expression levels in the morin + CCl₄ group were significantly higher than those of the CCl₄ group (P < 0.05).

Figure 6

The protein expression of α-SMA, collagen III, and collagen I. (1, 2) control group, (3, 4) morin group, (5, 6) CCl₄ group, (7, 8) morin + CCl₄ group. ^aP < 0.05 vs control group, ^cP < 0.05 vs morin group, ^eP < 0.05 vs CCl₄ group. The CCl₄ and morin + CCl₄ groups showed significantly increased expression compared to the control and morin groups (P < 0.05), and the expression levels in the morin + CCl₄ group were lower than those in the CCl₄ group (P < 0.05).

Figure 7

The protein expression of Nrf2, HO-1, and NQO1. (1, 2) control group, (3, 4) morin group, (5, 6) CCl₄ group, (7, 8) morin + CCl₄ group. ^aP < 0.05 vs control group, ^cP < 0.05 vs morin group, ^eP < 0.05 vs CCl₄ group. In the CCl₄ and morin + CCl₄ groups, the protein expression was increased compared to the control and morin groups (P < 0.05); the morin + CCl₄ group had a more significant change compared to the CCl₄ group (P < 0.05).